Shoe with molded elastomeric sole



1961 A. GREENBAUM 2,995,840

SHOE WITH MOLDED ELASTOMERIC SOLE Filed Jan, 11, 1960 uu u ggw ummmum ju I F I :r r

INVEN ARTHUR GREEN BAU United States Patent Office Patented Aug. 15, 1 961 2,995,840 SHOE WITH MOLDED ELASTOMERIC SOLE Arthur Greenbaum, Newton, Mass., assignor to American Biltrite Rubber Co., Inc., Chelsea, Mass., a corporation of Delaware Filed Jan. 11,1960, Ser. No. 1,712 1 Claim. (Cl. 36-195) This invention comprises an improvement in the manufacture of shoes having outsoles of tough resilient elastomeric compounds of natural or synthetic rubber or resinous material.

Soles of such material possess many advantages since they outwear leather, are waterproof and can be molded in any desired shape without waste and with or without an integral heel. 7 All these features contribute to an important degree in the reduction of shoemaking costs but heretofore serious difficulty has been encountered in pro ducing a reliable and permanent bond between an outsole of resilient elastomeric material and the corresponding elements of the shoe bottom. This difficulty has been due in a large measure to the fact that the sole material has a long resilient memory so that any initial stress set up in adhesively securing such a sole in even slightly curved condition in the shoe bottom continually fights the adhesive bond and so eventually breaks down the bond, causes separation of the outsole and failure of the shoe to give satisfaction to the wearer.

The present invention is based on a discovery that solves this long-standing problem. I have found that the secret of a permanent and reliable bond in the employment of an outsole of resilient elastomeric compound lies in giving to the sole a novel molded shape and contour characterized by a relatively thick marginal bead shaped to fit snugly against the outer peripheral wall of the upper and a thinner sole body of substantially uniform thick ness having an initial natural transverse concave curvature and being biased to retain permanently a transverse curvature in the shoe bottom corresponding to the convex contour of the insole and lasted margin of the upper to which it is to be adhesively secured. An outsole of such configuration and character does not fight the adhesive bond but tends always to reinforce and strengthen it and thus the useful life of the shoe is prolonged indefinitely.

An optional feature of the invention consists in molding the elastomeric sole with an integral heel portion and this may be finished to the proper size and shape in the molding operation, thus eliminating the attaching, trimming, scouring and breasting operations required in dealing with separate heels of conventional design.

There are other features of the invention that will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawings, in which FIG. 1 is a plan view of the sole,

FIG. 2 is a corresponding view in elevation,

FIG. 3 is a view in cross-section on the line 3-3 of FIG. 2 and on a larger scale, and

FIG. 4 is a cross-sectional view showing the sole as secured in a lasted shoe bottom.

The sole as shown in FIGS. 1 and 2 is molded as an integral unit of full length to constitute the complete tread surface of the shoe and includes a forepart 10, shank 11, and heel 12.

The forepart and shank portions of the sole are of sub stantially uniform thickness throughout except that they are bounded by a thicker marginal bead 13, slightly concaved in its inner upright face and having a narrow upper flat face knurled or otherwise ornamented. As herein shown this bead extends continuously about the sole ineluding its heel seat and is designed to make a snug waterproof engagement with the peripheral Wall of the upper. For that purpose each sole is given the exact contour in size and shape of the shoe of which it is to form a part.

The integral heel 12 is also shaped in the molding operation to the size and style required in the finished shoe and in order to reduce the weight of the sole the heel may, if desired, be recessed from its heel seat surface. As shown in FIG. 1 the recess 14 is shaped to provide a stout peripheral wall for the heel and this is further stabilized against distortion by a transverse tie 15.

The forepart l0 and shank portions are given in the molding operation a natural transverse curvature and the material thereof is given an initial bias to retain that curvature so that it tends when distorted always to reassume its initial. contour. This transverse curvature is the exact counterpart of the curvature of the shoe bottom .as determined by the last on which the shoe is to be made as suggested in FIG. 4. In that figure a lined upper 20 is shown as lasted upon a last 21 carrying on its curved bottom an insole 23. The lasting margins 22 of the upper are cemented to the outer face of the insole and the space between the margins is smoothly occupied by a filler 24. It will be seen that the insole, lasting margins and filler present an outwardly convex contour corresponding to the contour of the rounded last bottom and it is this curvature that is given to the inner surface of the molded sole. The outer surface of the sole is parallel thereto thus making the sole of uniform thickness between its marginal beads and in advance of the heel breast line.

The elastomeric material from which the sole is molded is a compound of natural or synthetic rubber of flexible and resilient texture. The compound is such that when it is cured in the sole in suitable molds it naturally assumes the desired outwardly convex contour and tends always to resist deformation and to return immediately to its initial contour after being forcibly distorted. It thus exerts a continuous resistance to any separation from the other components of the shoe bottom and exerts a continuous binding effect upon the adhesive bond securing it in the shoe bottom. The resilient memory of the material is of unexpectedly long duration, in most instances outlasting the normal life of the shoe of which it forms a part.

One satisfactory and typical compound for the molded sole is as follows:

ber and/or synthetic resins having equivalent characteristics.

While the sole is molded with a characteristic and important transverse curvature, as above described, the top surface of the head 13 is disposed in a single common plane, and this coincides with the parting plane of the molds, a feature which contributes to the economic production of the sole. It will be seen, therefore, that the top face of the bead has no longitudinal curvature from one end of the sole to the other. Accordingly, any longitudinal curvature imparted'td the sole in conforming it'to the shoe bottom sets up initial stress which causes the shank and forepart of the sole to hug the shoe bottom and, reinforce the adhesive bond in yet another aspect;

surface in conformity to the rounded contour of a last bottom, in combination with an outsole molded of tough resilient elastomeric compound having a relatively thick marginal bead, said bead having an inner concave surface, said bead inner surface fitting against the wall of the upper, said outsole having a thinner shank and torepart body of substantially uniform thickness; said outsole stifliy resisting transverse flexing and having an initial natural transverse concave surface complementary to the geonvex surface of the bottom of the upper and the bead having a height suflicient to completely house the edge portion of the bottom of the upper, said outsole being adhesively secured without initial stress of deformation to said convex contour of the insole and the lasted margin of the upper, and biased to retain permanently its transverse curvature in the shoe bottom, thus exerting a continuous binding effect upon the adhesive bonds securing the sole to the shoe bottom, the top surface of the marginal bead lying in a common plane from one end of the sole to the other.

References Cited in the file of this patent UNITED STATES PATENTS 2,527,414 7 Hallgren Oct. 24, 1950 2,918,735 Johnson Dec. 29, 1959 FOREIGN PATENTS 365,986 Great Britain Jan. 28, 1932 1,130,957

France 8, 19 56 

